1. Field of Invention
The present invention relates to a display. More particularly, the present invention relates to a backlight module for the display.
2. Description of Related Art
A liquid crystal display (referred as to LCD) is a thin, flat display device and uses very small amounts of electric power. The LCD has been widely used in all kinds of electronic devices such as cell phones, personal digital assistant, cameras, computer monitors, etc. Contrast ratio is one of the important quality factors of the LCD. It is defined by the ratio of the luminance of the brightest color like white to the luminance of the darkest color like black. In general, when displaying high definition video, the LCD requires thousands of different luminance to present colors of an image precisely. Therefore, the LCD manufactures attend to upgrading the contrast ratio of the LCD.
In modern technology, one of the methods to raise the contrast ratio of the LCD is the local dimming technology, which is to dim each light source individually in a backlight module of the LCD by adjusting current flowing through each light source.
The light source for the backlight module can be a fluorescent lamp or a light emitting diode (referred to as LED). Due to the recent technology, the fluorescent lamps may only be arranged parallel to each other, which means the fluorescent lamps only arranged in one direction. Therefore, the luminance variation is in one dimension, which is the direction the fluorescent lamps are arranged in, and is not sufficient for a two dimensional image that is displayed on the LCD. On the other hand, the LED may be arranged as a two dimensional array to match up the two-dimensional displaying image. However, currently, the price for a backlight module with LED is much higher. When the size of the LCD gets bigger, the price gap gets higher.
In the foregoing, a new display and a backlight module thereof is needed. The new display may use fluorescent lamps and may achieve two-dimensional local dimming at the same time to answer the industrial need and to benefit economic interests.